The performance of catalyst systems, particularly those that are nickel-based, can be significantly degraded by sulfur, and/or sulfur-containing compounds, which poison the catalyst. For instance, hydrogen sulfide, which is present in most common fossil fuel sources, can cause a significant poisoning of nickel-based anodes in solid oxide fuel cells (SOFC). In a specific example, a nickel-YSZ-based anode can typically show a 35-50% drop in power within 20 hours when even one ppm of hydrogen sulfide is present in the fuel. While desulfurizers can be employed to treat sulfur-containing reactants prior to reacting them on a nickel-based catalyst, such desulfurizers are often costly and/or bulky. Accordingly, a need exists for nickel-based catalyst systems having improved sulfur tolerance.